Ion channels are membrane proteins that are present in every cell of every living organism. The channels control flow of ions into and out of the cells and thus play a crucial role in cell functioning. Not surprisingly, ion channels constitute a very important class of drug targets. To efficiently develop new drugs, researchers need methods and devices that allow high-throughput screening of compounds (drug candidates) by their action on ion channels. Such drug screening methods and devices require mechanisms for measuring an ion channel's activity and mechanisms for applying compounds to the ion channels.
Ion channels are commonly studied with a technique called patch clamping. This technique involves measuring electrical signals (currents and/or voltages) from individual cells. The cells are arranged in an apparatus such that the magnitude of the electrical signal is directly related to the state of the ion channels, and in particular how much current they allow to pass. Thus, the technique allows direct electrical measurement of ion channel events in living cells, cell membranes and artificial membranes.
The whole-cell and perforated patch configurations of the patch-clamp are widely accepted as providing the best methods of measuring ion channel activity for drug screening. In these methods ion currents flowing through ion channels are measured directly and with high resolution by sensitive current amplifiers.
Unfortunately, current patch clamp instrumentation suffers from a variety of shortcomings, particularly with regard to high-throughput screening of ion channels, and particularly ligand-gated ion channels.